oddball vs eccentric person

oddball and eccentric person both are nouns.

Word	Noun	Adjective	Verb	Adverb
oddball	Yes	No	No	No
eccentric person	Yes	No	No	No

As nouns, oddball and eccentric person are synonyms defined as:

oddball and eccentric person: a person with an unusual or odd personality

Other synonyms of oddball include eccentric, flake, geek.

oddball (noun)	eccentric person (noun)
a person with an unusual or odd personality	a person with an unusual or odd personality